gh-156722, test_dtrace: Terminate tracing processes gracefully on timeout (#156753)

Send SIGTERM to the tracing process group before falling back to SIGKILL.

Author: stratakis

Lib/test/test_dtrace.py

@@ -84,21 +84,33 @@ def normalize_trace_output(output):
 
 
 USE_PROCESS_GROUP = (hasattr(os, "setsid") and hasattr(os, "killpg"))
+TERMINATE_TIMEOUT = 10
 
 def create_process_group(*args, **kwargs):
     if USE_PROCESS_GROUP:
         kwargs['start_new_session'] = True
     return subprocess.Popen(*args, **kwargs)
 
-def kill_process_group(proc):
+def terminate_process_group(proc):
     if USE_PROCESS_GROUP:
         try:
-            os.killpg(proc.pid, signal.SIGKILL)
+            os.killpg(proc.pid, signal.SIGTERM)
         except ProcessLookupError:
             pass
     else:
-        proc.kill()
-    proc.communicate()  # Clean up
+        proc.terminate()
+
+    try:
+        proc.communicate(timeout=TERMINATE_TIMEOUT)
+    except subprocess.TimeoutExpired:
+        if USE_PROCESS_GROUP:
+            try:
+                os.killpg(proc.pid, signal.SIGKILL)
+            except ProcessLookupError:
+                pass
+        else:
+            proc.kill()
+        proc.communicate(timeout=TERMINATE_TIMEOUT)  # Clean up
 
 
 def run_readelf(cmd):
@@ -163,7 +175,7 @@ def trace(self, script_file, subcommand=None, *, timeout=None,
         try:
             stdout, _ = proc.communicate(timeout=timeout)
         except subprocess.TimeoutExpired:
-            kill_process_group(proc)
+            terminate_process_group(proc)
             raise
         if check_returncode and proc.returncode:
             raise AssertionError(
@@ -361,7 +373,7 @@ def run_case(self, name, optimize_python=None):
             )
             stdout, stderr = proc.communicate(timeout=60)
         except subprocess.TimeoutExpired:
-            kill_process_group(proc)
+            terminate_process_group(proc)
             raise AssertionError("bpftrace timed out")
         except (FileNotFoundError, PermissionError) as e:
             raise unittest.SkipTest(f"bpftrace not available: {e}")
@@ -400,7 +412,7 @@ def assert_usable(self):
             )
             stdout, stderr = proc.communicate(timeout=10)
         except subprocess.TimeoutExpired:
-            kill_process_group(proc)
+            terminate_process_group(proc)
             raise unittest.SkipTest("bpftrace timed out during usability check")
         except OSError as e:
             raise unittest.SkipTest(f"bpftrace not available: {e}")